1. Field of the Invention
The present invention relates to a broadcasting signal receiver apparatus and a demodulation mode. More specifically, the present invention relates to a broadcasting signal receiver apparatus which receives a broadcasting signal of, for example, a cable television (referred to as a CATV hereinafter), and an apparatus for controlling a demodulation mode for controlling the demodulation mode upon demodulating a modulated received signal such as the broadcasting signal or the like.
2. Description of the Related Art
In recent years, following the progress of video digitalization, every country has started digital broadcasting through broadcasting media of satellite broadcasting, CATV broadcasting, and terrestrial broadcasting. Various kinds of transmission systems have been proposed as those suited for features of respective transmission lines. In particular, in the CATV broadcasting, various kinds of services such as a pay-per-view service or the like are provided taking advantage of stability and an interactiveness of the transmission line. According to a conventional CATV broadcasting system, an individual transmission system including a conditional access (referred to as a CA hereinafter) is adopted for each network operator, that is, each CATV broadcasting entity. Due to this, a manufacturer manufactures a set-top box (referred to as an STB hereinafter) and supplies the STB to each network operator based on standards of the network operator. A viewer concludes a viewing contract with each network operator and leases the STB from the network operator.
In these circumstances, in North America where 70% or more of TV viewers receive broadcasting programs through CATV, standards of separating apparatus parts such as the CA depending on each network operator from the STB for the CATV is disclosed by, for example, specifications for OpenCable (trademark), i.e., a prior-art technical literature of Cable Television Laboratories, Inc.: OpenCable™ Host Device Core Functional Requirements, Issued Specification, OC-SP-HOST-CFR-I10-020628, pp. 1-47, updated on Jun. 28, 2002, http://www.opencable.com/specifications/ as issued by Cable Television Laboratories, Inc for promotion of making STB's for CATV marketable. Based on the standards, each manufacturer is capable of making the CATV STB marketable integrally with a television receiver, a DVD player, a DVD recorder, or the like. In addition, the number of choices of products increases for consumers.
A security card which is provided depending on the network operator and which stores security information on each network operator and broadcasting signals from the network operator and a control program is mounted into the STB as disclosed by the prior art document. The security card is also referred to as a point of deployment (POD) module or cable card. When a viewer having this STB sees a toll broadcasting program, the viewer inserts the security card into the STB. Then, the security card generates a descrambling key based on CA information, and outputs the descrambling key to the STB. The STB descrambles and MPEG-decodes data on a toll broadcasting signal based on the inputted descrambling key, and acquires a video signal and a voice signal.
However, a viewer who sees only toll-free broadcasting programs does not necessarily mount the security card into the STB. If so, it disadvantageously takes a lot of time to select a channel for the broadcasting signal.